Electrical switch with bidirectional snap action actuation and spring contact blade therefor



Dec. 22, 1970 P. D. GROVER 3,550,055

ELECTRICAL SWITCH WITH BIDIRECTIONAL SNAP ACTION ACTUATION AND SPRING CONTACT BLADE THEREFOR Filed May 27, 1968 2 SheetsSheet l INVI'IN'I'OR. PHILIP D. GROVER AGENT Dec. 22, 1970 I p, GRQVER 3,550,055

ELECTRICAL SWITCH WITH BIDIRECTIONAL SNAP ACTION ACTUA'IION AND SPRING CONTACT BLADE THEREFOR Filed May 27, 1968 2 Sheets-Sheet 3 FIG. 7

FIG. IO

v 35A 36A 304 111 1111/ III/[# A ]%4 INVIIN'I'OR. 30C PHIUP D. GROVER United States. Patent Ofice 3,550,055 Patented Dec. 22, 1970 3,550,055 ELECTRICAL SWITCH WITH BIDIRECTIONAL SNAP ACTION ACTUATION AND SPRING CONTACT BLADE THEREFOR Philip D. Grover, Two Rivers, Wis., assignor to American Machine & Foundry Company, a corporation of New Jersey Filed May 27, 1968, Ser. No. 732,433 Int. Cl. H01h 61/04, 71/16 US. Cl. 337-100 20 Claims ABSTRACT OF THE DISCLOSURE This invention relates generally to snap switches having bimetal thermally responsive operators and to spring contact blades particularly adapted therefor.

The present invention is primarily concerned with electrical snap type switches having a bimetal operator arm with a resistance heating means and being of the type adapted to be embodied in thermally and photo controlled relays and the like. The thermally responsive actuator also is responsive to ambient temperature changes which causes varying switch actuating characteristics in the absence of adequate compensation.

The spring contact blades thereof while being particularly adapted to a thermally responsive switch are not limited to this singular environment and are required to provide positive bidirectional snap action characteristics. In other words, contact pressure must be retained until the moment engaging contacts open, and contacts must open and close rapidly at predetermined points of switch actuation. For this, substantially instantaneous force reversal is required. However, this alone is insufiicient .where closing contacts are subject to welding effects of sparking.

Accordingly, an object of the present invention is to provide a switch having a thermally responsive operator and presenting consistant actuation characteristics.

Another object of the present invention is to provide the foregoing switch which has positive bidirectional snap acting means for opening and closing contacts.

And another object of the present invention is to provide positive means for breaking contact welds prior to snap action operation.

Still another object of the present invention is to provide a switch capable of assembly with facility and minimal changes in both single and double throw configurations.

And still another object of the present invention is to provide the foregoing switch which is compact and of rugged and uncomplicated construction, can be manufactured with facility, and is reliable and positive acting.

Yet another object of the present invention is to provide a simple unitary spring contact blade means capable of positive bidirectional snap operation.

The present invention contemplates an electrical switch comprising an insulator stack; a pair of bimetal arms cantilevered from the stack, being spaced from and substantially parallel to each other, and deflecting in the same direction and substantially to the same degree in response to ambient temperature changes; one of the bimetal arms having heater means responsive to switch actuating signals, and an operator means at its free end; a supporting follower arm cantilevered from the stack between the bimetal arms and engaging the other of the bimetal arms to move in response to its deflection; at least one terminal contact supported by the stack providing a fixed contact face between the bimetal arms; a spring contact blade having at one end a contact face movable into and out of engagement with the fixed contact face, and its other end aligned for engagement and operation by the operator means to open and close the contact faces, the spring contact blade having an elongated slot closed at its ends dividing the blade into two substantially parallel reach portions between the blade ends; means connecting one of the reach portions between its ends to the supporting follower arm; and the other of the reach portions having a lateral deformation between its ends stressing the blade to deflect out of its normal unstressed plane such that movement of the operator end of the blade will cause wiping movement of the other blade end and snap action movement when a plane through the blade ends passes the connection of the one reach portion to rapidly open and close the contact faces.

The foregoing and other objects and advantages of the invention will appear more fully hereinafter from a consideration of the detailed description which follows, taken together with the accompanying drawings wherein several embodiments of the invention are illustrated by way of example. It is to be expressly understood, however, that the drawings are for illustration purposes only and are not to be construed as defining the limits of the invention.

FIGS. 1 and 2 are side elevational views of double and single throw switches, respectively, made in accordance with the present invention,

FIG. 3 is a plan view of a spring contact blade taken on line 3-3 of FIG. 1,

FIG. 4 is a sectional view taken on line 4-4 of FIG. 3,

FIGS. 5 and 7 are side elevational views similar to FIG. 1 illustrating modified forms of switches made in accordance with the present invention,

FIGS. 6 and 8 are fragmentary end elevations of the switches of FIGS. 5 and 7, respectively, each with portions broken away to more clearly illustrate the cooperating parts thereof,

FIG. 9 is a plan view similar to FIG. 3 of modified spring contact blade,

FIG. 10 is a sectional view similar to FIG. 4 and taken on line 1010 of FIG. 9, and

FIGS. 11 and 12 are sectional views similar to FIG. 10 each illustrating a different form of deformation.

Referring now to the drawings and particularly to FIGS. 1, 3 and 4, a switch 1 is provided at one end with an insulator stack means 2, in this instance, comprising six sequentially disposed dielectric spacer members 3 to 8 connected together by means 9 which may be nuts and bolts, rivets or any other suitable fastening means including clips and clamps which are well known in the art.

A pair of terminal contact members 10 and 12, which extend through the stack 2 and are retained thereby, are spaced from each other by the spacer member 5 and are provided with opposed fixed contact faces 11 and 13, respectively, disposed in spaced face to face alignment. An elongated supporting blade arm or member 14, which is cantilevered or has one end fixed between the spacer members 6 and 7, extends along a plane therefrom on the same side of the stack 2 as are the fixed contact faces 11 and 13 and terminates in a free end which is offset from the plane of the member in a direction away from contact terminals 10 and 12 to provide a bearing or foot portion 16. The supporting member 14 having lateral flanges 15, as shown, is between its end of substantially U-shaped cross-section to provide a desired degree of longitudinal rigidity.

An elongated bimetal blade compensator arm or member 20, which is cantilevered or has one end fixed between the insulator members 7 and 8, extends therefrom in the same direction as and along a plane substantially parallel to member 14, and terminates in a free end with a transverse flange 21 substantially normal to the blade plane and which extends in a direction toward the terminal contact members 10 and 12. The fixed ends of the blade arms or members 14 and 20 are spaced from each other by the spacer member 7 while the foot portion 16 bears against the bimetal blade and is spaced from the end flange 21 to prevent interfering engagement therebetween. An elongated terminal members 22 is retained at one end in the stack 2 in contact with the fixed end of the bimetal blade 20, and extends axially therefrom and oppositely thereto.

Another elongated bimetal blade provides an operator arm or member 25, which is cantilevered or has one end retained between spacer members 3 and 4, extends therefrom in the same direction as and in a plane substantially parallel to the blade compensator arm 20 and terminates in a free end provided with operator means 27. The operator means 27 is provided with a member 28 which is axially aligned with and adjustable toward and away from the end flange 21 to vary the size of a gap formed therebetween. A resistance heater means 26 is mounted on the blade operator arm 25 for switch actuation, as will be further discussed.

A spring contact blade 30 is provided at one end with contact faces 31 and 32 which are aligned to engage the fixed contact faces 11 and 13, respectively, and at its other end with an operator portion 33 which is disposed between the end flange 21 and the member 28 of the operator means 27. An elongated logitudinal slot 34 is laterally offset and divides the blade 30 into two substantially parallel flights, reaches or strap portions 35 and 37 which are connected together by the spring contact blade ends. One of the reaches, in this instance the wider reach 37, is connected intermediate its ends by any suitable means 18, such as a rivet or a spot weld, to a pedestal, mounting or support portion 17 of the supporting member 14 to mount the spring contact blade 30. The narrower reach 35 is provided with a transverse portion 36 intermediate its ends which is arcuately deformed out of the normal unstressed plane of the blade and makes the reach 35 shorter than the reach 37.

The foreshortening of the reach 35 stresses the blade 30 and exerts a warping, bending or deflection force to move the blade end portions out of the normal unstresed blade plane causing contact face 31 to engage the fixed contact face 11 and the operator blade end 33 to engage the member 28 of the operator means 27. This foreshortening also exerts a twisting movement or force on the reach 37 so that the angle of deflection along the side of the blade 30 partly formed by the reach 35 is greater than the angle of deflection along the opposite side thereof.

T make the operator end 33 of the blade 30 more rigid, a deformation or formed groove 39 may be pro vided therein which extends longitudinally into the adjacent portion of the reach 37, as best shown in FIG. 3. The deflection of the spring contact blade 30 resulting from the deformation 36 can be increased, as shown in FIG. 2, by providing a laterally disposed crease or bend 38 across the reach 37 between its connection to the pedestal 17 and the end of the axial groove 39, as best shown in FIG. 3.

The double throw switch 1 can be modified with facility to provide a single throw switch 40, as shown in FIG. 2. The terminal contact member 12 with its fixed contact face 13, accordingly, is not required and preferably is omitted from the switch 40 which has a modified stack 41. The difference between the stacks 2 and 41 is the omission of the spacer member 6 which also is not required. Omission of the terminal contact member 12 and spacer member 6 reduces the space between the planes of the terminal contact member 10 and the supporting blade member 14. Therefore, a smaller mounting pedestal or supporting portion 42 is provided in lieu of the pedestal 17. The switch 40 also illustrates a further modification which involves providing a bimetal blade arm 43 with an end flange 44, corresponding to the blade with its flange 21. The bimetal arm 43 extends through the stack 41 and has an integral terminal portion 45 corresponding to the terminal member 22.

The switch 40, as shown, is of normally closed configuration which alternatively can be of normally open configuration. Although not shown, this is accomplished by omitting the spacer member 4 and the terminal contact member 10 with its fixed contact face 11 in lieu of the omission of the spacer member 6 and the terminal contact member 12 with the fixed contact face 13.

All of the terminal members 10, 12 and 22 and the blade members 14, 20, 25, 30 and 43 are made of electrically conductive material while the resistance heater means 26 is provided with suitable terminal portions for connection to an energization source (not shown). The bimetal operator blade arm; is made of the same material as are the bimetal blade arms 20 and 43. The member 28 of the operator means 27 and end flange 21 are equally spaced from stack 2 in switch 1 and, similarly, this operator means member and the end flange 44 are equally spaced from stack 41 in switch 40. The bimetal members 25 and 20 have the same rate of deflection due to temperature change and present substantially equally long movable arms.

Therefore, ambient temperature change causing the arm 25 to deflect and alter the position of the member 28 of the operator means 27 relative to the spring contact blade also will cause the bimetal arm 20 to deflect an equal amount and in the same direction which is accompanied by follower movement of the supporting blade member 14 and the spring contact blade 30 supported thereby. Accordingly, switch 1 is provided with compensating means for ambient temperature changes as is switch 40 which reacts to such changes in a similar manner. Inasmuch as both of the switches here-to-fore described operate substantially in the same way, only the operation of switch 1 will be discussed.

As shown in FIG. 1, switch 1 is in its normal stable or unoperated condition in which the movable contact face 31 engages the fixed contact face 11 to electrically connect the terminals 10 and 22 through the bimetal compensator blade member 20, the supporting blade member 14, the spring contact blade 30 and the closed or engaging contact faces. In the unoperated condition the spring contact blade member 30, including the reach portion 37, is arced as a result of the foreshortening of the reach portion and both blade ends are offset toward the operator blade arm 25 from the normal plane of the contact blade member which extends through the connection of the reach portion 37 to the pedestal 17 by the fastening means 18. The reach portion 35 actually forms a tension member exerting a force along a plane which extends through the ends of the spring contact blade member 30. Thus, the spring contact blade member 30 provides a classic past center configuration.

When an actuating signal is applied to switch 1, current will flow in the resistance heater means 26. The resulting heat that is created will cause the bimetal operator arm 26 to deflect accordingly, which moves the operator means 27 and drives the operator end 33 of the spring contact blade member 30 toward the flange 21. The flange 21 is a limit stop which blocks the operator end 33 from being moved excessively when the spring contact blade member 30 is operated.

The reach portion 37 from its connection to the operator end 33 acts as a lever as the operator end moves toward flange 21. This levered movement of the operator blade end 33 exerts a pull on the reach portion 35 which biases or urges the contact end of the spring contact blade member 30 for planar movement and results in a wiping movement between the movable contact face 31 and the fixed contact face 11 to break any weld therebetween previously caused by sparking. Inasmuch as the support connection is laterally offset from longitudinal centerline of the spring contact blade 30 its contact end also is subject to a twisting force which enhances the wiping eflects. Simultaneously, the force plane of the reach portion 35 is pivoted about its end at the contact end of the spring contact blade member 30 until it passes the connection of the reach portion 37.

At this point. the warping, bending or deflection force resulting from the deformation .36 rapidly reverses and acts on the spring contact blade member 30 causing its contact end to move the contact face 31 out of engagement with the fixed contact face 11 and the contact face 32 into engagement wtih the fixed contact face 13. Simultaneously, this force also urges the operator end 33 of the blade member 30 toward the flange 21. The switch 1 is now in its unstable or actuated condition or state, electrically connecting the terminal members 12 and 22 thorugh the bimetal compensator blade arm 20, the supporting blade member 14, the spring contact blade member 30 and the closed or engaging contact faces 32 and 13.

The spring deflection force of the levered reach portion 37 with the relative position of the operator end 33 must be capable of overcoming the warping force of the deformation 36 urging the operator end toward the flange 21. Therefore, when the switch actuating signal terminates and the heat from the resistance means 26 subsides, the operator blade arm 25 oppositely deflects moving the op erator means 27 away from the flange 21 and follower movement of the operator spring contact blade end 33 occurs. When the operator end 33 moves sufliciently away from flange 21 to create another across or past center condition, the warping force resulting from the deformation 36 will again reverse and cause the contact end of the spring contact blade member 30 to snap back to its original position and reestablish the original contact face engagement. It should be understood that the follower movement of the operator end 33 also causes a wiping action between the contact faces 32 and 13 prior to snap action contact separation.

Two additional modifications of the switch 1 are shown in FIGS. and 7, each being of double throw configuration and capable of further modification to a single throw configuration (not shown).

Referring now to FIGS. 5 and 6, a modified double throw switch 50 is provided with the insulator stack 2, the terminal contact members and 12 having the respective fixed contact faces 11 and 13, the bimetal operator blade are 25, the resistance heater means 26, the operator means 27 and spring contact blade member 30, as provided in switch 1.

An elongated planar bimetal compensator blade or blade arm 57, which is provided in lieu of the compensator blade member 20, is cantilevered or has one end retained between the insulator members 7 and 8 of the stack 2 and extends therefrom to terminate in a free end. The blade arm 57 is free at one end which is reduced in width to provide tongue portion 58.

A supporting blade member 51, which is provided in lieu of the blade member 14, extends through the stack 2 between the insulators 6 and 7 to provide an integral terminal portion 52 which corresponds to the terminal member 22 of switch 1 or the terminal portion 45 of switch 40. The blade member 51 is provided with lateral flanges 53 and an end flange 54 with a central slot which correspond to the lateral flanges and the foot portion 16, respectively, of the supporting member 14. Instead of the foot portion 16 bearing upon the bimetal blade arm 20 and following its movement as in the switch 1, in this instance the tongue portion 58 extends through the slot 55 in the flange 54 to provide a slidable positive connection. Therefore, the compensator blade arm 57 is a driving member when it moves and correspondingly moves the supporting or driven follower member 51. The supporting blade member 51 also has a rigid pedestal, mounting or supporting portion 56, corresponding to the pedestal 17, for mounting the spring contact blade member 30.

The switch 50 is provided with more positive means for causing wiping movement between engaged contact faces which is more positive than levered end of the reach portion 37 which extends from its connection at the pedestal 17 to and including the operator end 33 of the spring contact blade 30. As shown in FIGS. 5 and 6, the supporting portion or pedestal 56 is formed to provide a hinge point 61 for one end of a rigid operator lever 60 which extends through the slot 34 of the spring contact blade 30. The other or operator end of the lever 60 has a notched end face 62 to engage the end of the slot 34 closed by the blade operator end 33, and preferably may be formed, as shown, to provide a portion 63 for engagement by the member 28 of the operator means 27.

Referring now to FIGS. 7 and 8, a further modified switch 70 is provided with the stack 2, terminal contact members 10 and 12, bimetal operator blade arm 25, heater means 26, operator means 27 and the spring contact blade 30 of the switch 50. In lieu of the unitary supporting blade member 51, a supporting blade member 71 with a separate terminal member 76 are provided. The blade member 71 has lateral flanges 72 and an end flange 73 corresponding to the flanges 53 and 54, respectively, and a resilient mounting or supporting portion 75 for mounting the spring contact blade 30. The resilient supporting portion 75 may be connected as a separate piece to or stamped out and formed from the supporting member 71. The end flange 73 in this instance has a pair of open slots 74 each in the opposite side thereof to provide a reduced or necked down portion movable in a slot 78 in the free end of an elongated bimetal compensator blade arm 77. The compensator arm 77, like the arm 57, is retained between the insulator members 7 and 8.

A slot is provided in the supporting member 71 adjacent the resilient supporting portion 75, or is provided thereby if such portion is formed therefrom. Similar to the arrangement of switch 50, a rigid operating lever 80 extends through the slot 34 of the spring contact blade 30. The lever 80* is provided with notched end faces 81 and 82, one for engaging the edge of the slot in the supporting member 71 and the other for engaging the end of the slot 34 closed by the spring contact blade operator end 33. The operator end 83 of the lever 80 may be formed for engagement by the member 28 of the operator means 27, as shown.

Although not shown, in view of the arrangements of switches 1 and 40, it should be understood that the supporting blade follower members 51 and 71 may be shortened and the free ends of the respective compensator blade arms 57 and 77 may be formed to provide end flanges in switches 50 and 70', respectively, corresponding to flanges 21 and/or 44.

The spring contact blade 30, best shown in FIGS. 3 and 4, may be modified as shown in FIGS. 9 and 10. The modified spring contact blade 30A also is provided at one end with contact faces 31 and 32 (only 31 being shown) and an operator portion 33A corresponding to the operator end 33. An elongated slot 34A, corresponding to the slot 34, is provided along the longitudinal centerline of the blade 30A forming reach or flight portions 35A and 37A which are equal in width and are joined to each other by or are integral with the blade ends. The reach portion 37A is to be connected to a supporting member while the reach portion 35A is provided with a deformation 36A of V-shape in cross-section.

The arcuate deformation 36 and the V-shaped deformation 36A each extend only in one direction out of the normal unstressed planes of blades 30 and 30A, respectively. It should be understood that a deformation can extend out of the plane of the blade in two directions by oppositely forming the deformation ends. As shown in FIG. 11, a spring contact blade 30B is provided with sharp bends to provide a deformation 36B which is of Z-shape in cross-section while a blade 30C is shown in FIG. 12 as having a deformation 36C which is formed of a compound are or is convoluted in cross-section.

It should be understood that the bend 38 and/or the axial groove 39 may be provided in any of the blades 30, 30A, 30B or 30C, and that each of the deformation-s 36, 36A, 36B or 36C may be provided in a blade with a laterally offset slot 34 or a slot 34A which is disposed on the longitudinal centerline of the blade.

Although several embodiments of the invention have been illustrated and described in detail, it is to be expressly understood that the invention is not limited thereto. Various changes may be made in the design and arrangement of the parts without departing from the spirit and scope of the invention as the same will now be understood by those skilled in the art.

I claim:

1. In an electrical switch, a combination comprising:

two thermally responsive means, one operating a spring contact blade for switch actuation in response to actuating signals and the other compensating said switch for ambient temperature changes;

contact means providing at least one fixed contact face between said two thermally responsive means; an elongated spring contact blade disposed between said two thermally responsive means, having at one end a contact face aligned for movement into and out of engagement with said fixed contact face by blade operation, and its other end aligned for movement by said operating means and toward and away from said compensating means to operate said blade;

means connecting said blade to said compensating means and engaging said blade between its ends and laterally offset toward one side thereof;

said blade having a deformation disposed between said blade ends and laterally offset toward the side thereof opposite from said connecting means;

said deformation exerting a warping force on said blade, and along a plane through said blade ends and on one side of said blade connection toward one of said thermally responsive means; and

movement of said other blade and causing substantially planar movement of said one blade end and pivotal movement of the plane of the warping force to the other side of said blade connection whereupon the warping force causes said one blade end to rapidly move in the same direction of movement of said other blade end.

2. The electrical switch in accordance with claim 1, wherein:

said contact means provides another fixed contact face;

said fixed contact faces being disposed in spaced face to face alignment; and

said spring contact blade having at said one blade end another contact face aligned for movement into and out of engagement with said other fixed contact face by blade operation.

3. The electrical switch in accordance with claim 1, wherein:

said spring contact blade having an elongated slot closed at its ends, and a pair of reach portions substantially parallel to each other between said blade ends each being disposed on a different side of said slot;

8 one of said pair of reach portions being engaged by said connecting means; and said deformation extending laterally across the other of said pair of reach portions. 4. The electrical switch in accordance with claim 3,

and

said slot being disposed along the longitudinal center of said spring contact blade. 5. The electrical switch in accordance with claim 3, 10 and said slot being laterally offset from the longitudinal center of said spring contact blade.

6. The electrical switch in accordance with claim 3, and said thermally responsive operating means including:

a cantilevered bimetal operator arm;

means connected to said arm and providing heat thereto in response to switch actuating signals causing said arm to deflect toward said compensating means; and

blade engaging means connected to the free end of said arm for axial adjustment toward and away from said compensating means, and causing said one blade end to move in response to deflection of said arm to operate said spring contact blade.

7. The electrical switch in accordance with claim 3, 25 and said thermally responsive compensating means includa cantilevered bimetal compensator arm;

a cantilevered follower arm substantially parallel to and spaced from said bimetal arm in a direction toward said operating means, and having an end portion engaging said bimetal arm adjacent the free end thereof;

said connecting means connecting said one reach portion to said follower arm for connecting said spring contact blade to said compensating means.

8. The electrical switch in accordance with claim 7,

wherein:

the free end of said bimetal arm is a flange extending therefrom toward said operating means; and

said flange being aligned with said other blade end for engagement thereby to limit the movement thereof toward said compensating means.

9. The electrical switch in accordance with claim 7,

wherein:

the free end of said follower arm has a foot portion extending toward said bimetal arm and bearing on the engaged portion thereof.

10. The electrical switch in accordance with claim 7,

wherein:

the free end of said follower arm has a flange portion extending therefrom toward the engaged portion of said bimetal arm; and

on of said portions having at least one slot and the other of said portions being formed to extend through said slot connecting said portions for movement in unison when said bimetal arm deflects and for relative longitudinal movement therebetween.

11. The electrical switch in accordance with claim 7,

and said thermally responsive operating means including:

a cantilevered bimetal operator arm spaced from and substantially parallel to said bimetal compensator arm;

each of said bimetal arms being responsive to ambient temperature changes in the same direction as the other;

means connected to said operator arm providing heat thereto in response to switch actuating signals causing said operator arm to deflect toward said compensator arm; and

blade engaging means connected to the free end of said operator arm for axial adjustment toward and away from said operator arm, and causing said one blade end to move in response to deflection of said operator arm to operate said spring contact blade.

12. The electrical switch in accordance with claim 11,

wherein:

the free end of said compensator arm is a flange extending therefrom toward said operator arm and being aligned with said blade engaging means; and

said flange being positioned to engage and limit the movement of said other blade end toward said compens'ating means.

13. In an electrical switch, a combination comprising:

a stack of insulator members;

two bimetal arms cantilevered from said stack and disposed in spaced substantially parallel relationship to each other, each deflecting in the same direction as the other in response to an ambient temperature change;

one of said bimetal arms having blade operator means connected to its free end, and means for providing heat in response to switch actuating signals causing said one arm to deflect and move said operator means toward the other of said bimetal arms;

a follower arm cantilevered from said stack between said bimetal arms and at its free end engaging said other of said bimetal arms adjacent the free end thereof, said supporting arm moving in response to deflection of said other of said bimetal arms;

at least one terminal contact extending through said stack and providing a fixed contact face disposed between said one of said bimetal arms and said follower arm;

an elongated spring contact blade at one end having a contact face movable into and out of engagement with said fixed contact face by snap action operation of said blade for switch actuation, and its other end being an operator portion aligned with said operator means and being movable toward and away from the free end of said other said bimetal arms between two terminal positions;

said spring contact blade having an elongated slot dividing said blade between its ends into two substantially parallel reach portions;

means for connecting one of said reach portions between its ends to said follower arm;

said other reach portion having a deformationproviding a force causing said blade to warp and being exerted along a plane passing through the ends of said warped blade and on one side of the blade connection means toward one of said bimetal arms;

movement of said operator blade end between its ter minal positions causing wiping movement of said movable contact face relative to said fixed contact face, and pivoting of the warping force plane at the blade contact end and past the blade connecting means causing overcenter snap action operation of said blade.

14. In an electrical switch having operator means,

mounting means and at least one fixed contact face, the combination capable of bidirectional snap action operation for switch actuation comprising:

an elongated unitary spring contact blade bidirectionally movable at its ends substantially normal to the plane of said blade, and being connected between its ends and laterally offset from its longitudinal center to said mounting means; one of the ends of said blade having a contact face movable into and out of engagement with said fixed contact face by said one end when said blade is operated;

the other of the ends of said blade being aligned for engagement and movement by said operator means;

said blade having a deformation disposed between its ends and laterally offset from the longitudinal center thereof in a direction opposite from the blade connection;

said deformation exerting a warping force on said blade,

and along a plane on one side of said blade connection and through the ends of said blade;

movement of said other blade end causing substantially planar movement of said one blade end, and pivotal movement of the warping force plane around said one blade end and past said blade connection; and

the warping force causing said one blade end to rapidly move in the same direction as said other blade end when the warping force plane is moved past said blade connection. 15. The electrical switch in accordance with claim 14, wherein:

said spring contact blade has an elongated longitudinal slot closed at its ends and a pair of substantially parallel reach portions between said blade ends each on a different side of said slot; one of said reach portions being connected to said mounting means; and said deformation extending laterally across said other of said reach portions. 16. The electrical switch in accordance with claim 15, and

said slot being disposed along the longitudinal center of said blade. 17. The electrical switch in accordance with claim 15, and

said slot being laterally offset from the longitudinal center of said blade. 18. The electrical switch in accordance with claim 15, and

said other blade end having a longitudinal groove extending into said one reach portion adjacent thereto. 19. The electrical switch in accordance with claim 15, and

said operator means moving said other blade end in one direction against the warping force and causing deflection of said blade, and the force of deflection being greater than the warping force and moving said other blade end in the opposite direction toward said operator means. 20. The electrical switch in accordance with claim 19, and

said one reach portion having a laterally disposed bend offsetting said other blade end toward said operator means.

References Cited UNITED STATES PATENTS 3,076,070 1/1963 Millerwise 200-67( D) 2,658,975 11/1953 Zuckerman 3375 3 3,359,389 12/1967 Landin 337347 2,700,083 1/1955 Harmon 337-X 2,599,473 6/1952 Miller 33738 2,189,996 2/1940 Riche 337-53X BERNARD A. GILHEANY, Primary Examiner D. M. MORGAN, Assistant Examiner US. Cl. X.R.

ZOO-67; 337--347, 378 

